(a) Technical Field
The present invention relates to an active hood system for a vehicle. More particularly, the present invention relates to an active hood system for a vehicle which allows a user to easily restore the positions of an actuator and a hood operated at the time of a pedestrian collision with little force.
(b) Background Art
In general, a vehicle has an engine compartment provided at the front part thereof, wherein the engine compartment is opened or closed by a hood.
The hood is a part adapted to shut off engine noise by shielding the engine compartment as well as to open or close the engine compartment, in which the hood is connected to the top of the engine compartment generally at the left and right sides of the rear end thereof through hinge assemblies in such a manner that the hood can be rotated about the hinge assemblies to open or close the engine compartment.
However, such a hood is known as a part inflicting a heavy injury upon a pedestrian at the time of a pedestrian collision. Thus, an active hood system is recently applied to such a hood, so that a space capable of absorbing the pedestrian's impact energy can be secured between the hood and the engine compartment in a pedestrian collision accident.
The active hood system is a system for lifting a hood so as to protect a pedestrian at the time of a pedestrian collision, and serves as a kind of a pedestrian-protection safety device which can reduce the pedestrian's injury index as well as absorb the pedestrian's shock in a pedestrian collision accident.
In a conventional active hood system, if a sensor mounted on a front bumper senses a pedestrian collision when a pedestrian collides against the front bumper, a controller operates an actuator in accordance with a sensing signal of the sensor to lift the rear end of the hood, so that a shock-absorbing space can be secured between the hood and the engine compartment.
At this time, if the controller receives the sensing signal from the sensor and drives the actuator, a hinge assembly is lifted by the actuator as it is driven, and at the same time, the rear end of the hood, to which the hinge assembly is connected, is lifted, thereby pushing up the pedestrian to absorb the pedestrian's shock.
However, such a conventional active hood system has a problem as follows.
Various actuators are applied to such an active hood system to lift the rear end of a hood, in which after the active hood system is operated, it is impossible for a user to manually restore the actuators to the original positions thereof, i.e. to the state prior to operation. That is, due to the excessive force typically exerted by springs that have raised the rear end of the hood after the actuators were operated, it is difficult for a user to manually lower and close the lifted hood, which deteriorates the user's convenience.
Such a problem will be described with reference to FIG. 1 which shows a construction of a conventional hinge assembly, wherein as shown in the drawing, an actuator 20 has springs 21 exerting a strong spring force to raise a considerably heavy hood at the time of a pedestrian collision, and a hinge assembly 10 having a four-bar link mechanism is provided between a hood (not shown) and the actuator 20.
The hinge assembly 10 includes a hinge arm 11 fixed to the hood, and two links 12 and 13 provided between and connected to the hinge arm 11 and the actuator 20, in which the links 12 and 13 are lifted and rotated as the actuator 20 is being driven, which causes the rear end of the hood to be lifted, and at the same time, the actuator 20 is lifted, which causes the hinge arm 11 and links 12 and 13 to be pushed upward.
In order to restore the actuator after the actuator was operated as described above, it is necessary to lower the hood so that the springs can be compressed. However, due to the excessive spring force, it is impossible for the user to directly lower the hood to compress the springs and at the same time to restore the position of the actuator. Consequently, the actuator can be restored only in a vehicle after-service (AS) center or a vehicle repair center.
As a result, after the pedestrian collision and the operation of the active hood system, the vehicle should be moved to such a vehicle AS center or a vehicle repair center in a state in which the hood is deployed, that is the rear end of the hood is raised, and if the vehicle is driven in such a state, the possibility of accident occurrence is increased.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.